Elixir check if a function has been called from a ExUnit test?

Question

Is there a way to check if a function has been called from a ExUnit test case? I have a function that calls IO.puts and I would like to test and verify that something is being outputted to STDOUT via a test case.

I saw this: http://erlang.org/pipermail/erlang-questions/2005-July/016259.html . But I was hoping there might be a simpler way of doing this with ExUnit.

Is there a way to check and see if my function calls IO.puts? Or at least check and see if something has been sent to STDOUT?

Answer 1

If you just want to test the STDOUT via a test case, I think CaptureIO can be used. The following has the spec and sample code.

https://hexdocs.pm/ex_unit/master/ExUnit.CaptureIO.html

You could mock the method calls using some mocking libraries, but for STDOUT, the above one would be simpler approach.

• https://github.com/jjh42/mock
• https://github.com/josephwilk/amrita